Electric switch



Dec. 30, 1930. Q TH W 1,787,291

' ELECTRIC SWITCH Filed Nov. 22 1928 l8 I I! I9 25 22 Inventor:

8 Carl Thumim,

gfi l His Attorney.

Patented Dec. 30, 1930 UNITED STATES PATENT OFFICE CARL THUMIM, OFPHILADELPHIL'PENNSYLVANLA, ASSIGNOR '10 GENERAL ELECTRIC COMPANY, ACORPORATION OF NEW YORK ELECTRIC swrrcn Application filed November 22,1928. Serial No. 321,190.

My invention relates to electric switches and particularly to switchesof the type in which one of the cooperating contacts is a wedge memberand the other comprises yielding plates which engage the opposite facesof the wedge member. An object of my invention is the provision of animproved switch of this character whereby any are that is drawn upon theopening of the switch does not burn the contact faces.

My invention will be better understood from the following descriptiontaken in connection with the accompanying drawing, and its scope will bepointed out in the appended claims.

Referring to the drawing, Fig. 1 is a cross section of an electricswitch of the liquid break type embodying my invention; Fig. 2 is anenlarged view showing one of the fixed contacts thereof; Figs. 3, 4 and5 are viewson a still larger scale showing the action of the contactsrespectively in three successive positions.

- The switch in which I have chosen to illustrate my invention comprisesthe tank 1 containing insulating liquid 2 and having the top 3 enclosingthe operating mechanism 4.

Through the top extend the insulator bush ings 5 and studs 6 to theinner ends of which are secured the fixed contacts 7. Arranged to bridgethe two fixed contacts 7 is the movable bridging contact wedge 8connected with the operating mechanism by means of the operating rod 9.The fixed contacts each comprise a plurality of fingers which engageopposite faces of the movable wedge 8. In the present embodiment of myinvention, I have shown two pairs of mainv contact fingers 11 and twopairs of auxiliary or arcing contact fingers 12. The construction of them in contacts 11 is disclosed and claimed in the copending applicationof George H. Tovey and myself, Serial No. 244,596, filed January 5,1928, and assigned to the same assignee as the present application. Theconstruction of the auxiliary or arcing contact fingers 12 comprisingthe invention in the sure.

conductor 17 is the sheet metal member 18 which preferably is bent up toreceive the end of the support 16 and to which is secured the post 19.-This post passes through an opening in support 16, there beingsufficient clearance provided to permit of a certain amount of freedomof movement of the contact plate on the support. Engaging the outerrounded end of the post 19 is the leaf spring 20 which together with thesupport 16 is secured to the member 13 by the bolt 21. The parts abovedescribed are so constructed that in the open circuit position of theswitch, such being shown in Fig. 3, the two opposite contact plates 14rest against each other at their rear portions so that they may pivot,or rock, with respect to each other and form with each other an. anglewhich is materially less than the angle of the cooperating contact 8. Asthe latter contact rises in the switch closing operation it firstengages the flaring portions or tips 15 of the contact fingels-whereuponthe plates 14 first rock about their rear portions being opposed by thesprlngs 20. lrVhen the parts reach a positron approximately like thatshown in Fig. 4 the contact plates 14 begin to separate bodily until thefully closed position is reached such as shown by Fig. 5. During thislatter movement the effect of the springs 20 has been reinforced by theresilence of the supports 16, the'combined force of the springs andsupports producing the required contact pres- Upon opening the switchthe parts move in the reverse manner. Asa result, the points of actualcontact between the wedge 8 and. the plates 14 passes from the two flatside faces 22 in the case of the wedge to the rounded edge portion 23.In the case of the contact plates 14, the points of contact pass fromthe flat contact faces 24 thereof over the rounded edges 25 to the faces26 of the heavy flared portions 15. Thus upon the opening of the switchthere is no arc drawn between the contacts at those faces thereof whichare depended upon for current transmission in the closed position. Allburning of those faces therefore is avoided. It will be obvious thatupon closing the switch any are that strikes before actual contact takesplace will also be between points of the cooperating contacts other thantheir flat contact faces, so that no burning of those faces will occuras the switch is closed.

What I claim as new and desire to secure by Letters Patent of the UnitedStates is:

1. An electric switch comprising a wedge contact member, a cooperatingcontact member having contact plates arranged to engage opposite sidesof the wedge contact member, and means for supporting said contactplates and yieldingly opposing outward movement thereof. said meansbeing loosely connected with said contact plates to cause them to engageeach other at their rear portions and rock about the point of engage--ment during the withdrawal movement of the wedge.

2. An electric switch comprising a wedge contact member, a cooperatingcontact member having contact plates arranged to engage opposite sidesof the wedge contact member, and means for supporting said contactplates and yieldingly opposing outward movement thereof, said contactplates having outwardly flaring front portions and said means beingloosely connected with contact plates and arranged to bias their rearportions towards each other when the wedge member is withdrawn wherebythe final contact is made with said flaring portions.

3. An electric switch comprising a wedge contact member, a cooperatingcontact comprising plates having flat contact faces for engagement withthe sides of the wedge member and having outwardly flaring arcing tips,means for yieldingly pressing said plates against the wedge member andfor causing them to engage at their rear portions and rock toward eachother when the wedge'is withdrawn therefrom, the point of contact of thewedge with the plates being thereby moved to the flaring arcing tips.

4. An electric switch comprising a movable wedge contact member, a pairof coopcrating contact plates having outwardly flaring tips, yieldablesupports therefor, and springs for opposing outward movement of saidplates, said springs being effective initially to move the plates bodilytoward each other upon the withdrawal of the wedge contact andsubsequently to cause the plates to engage at their rear portions androck thereon whereby the points of final contact move to the flaredportions.

In witness whereof, I have hereunto set my hand this 20th day ofNovember, 1928.

CARL THUMIM.

